<?php
/**
 * This file contains the error handler application component.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright Copyright &copy; 2008-2011 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

Yii::import('CHtml',true);

/**
 * CErrorHandler handles uncaught PHP errors and exceptions.
 *
 * It displays these errors using appropriate views based on the
 * nature of the error and the mode the application runs at.
 * It also chooses the most preferred language for displaying the error.
 *
 * CErrorHandler uses two sets of views:
 * <ul>
 * <li>development views, named as <code>exception.php</code>;
 * <li>production views, named as <code>error&lt;StatusCode&gt;.php</code>;
 * </ul>
 * where &lt;StatusCode&gt; stands for the HTTP error code (e.g. error500.php).
 * Localized views are named similarly but located under a subdirectory
 * whose name is the language code (e.g. zh_cn/error500.php).
 *
 * Development views are displayed when the application is in debug mode
 * (i.e. YII_DEBUG is defined as true). Detailed error information with source code
 * are displayed in these views. Production views are meant to be shown
 * to end-users and are used when the application is in production mode.
 * For security reasons, they only display the error message without any
 * sensitive information.
 *
 * CErrorHandler looks for the view templates from the following locations in order:
 * <ol>
 * <li><code>themes/ThemeName/views/system</code>: when a theme is active.</li>
 * <li><code>protected/views/system</code></li>
 * <li><code>framework/views</code></li>
 * </ol>
 * If the view is not found in a directory, it will be looked for in the next directory.
 *
 * The property {@link maxSourceLines} can be changed to specify the number
 * of source code lines to be displayed in development views.
 *
 * CErrorHandler is a core application component that can be accessed via
 * {@link CApplication::getErrorHandler()}.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @version $Id: CErrorHandler.php 3314 2011-06-24 14:47:47Z qiang.xue $
 * @package system.base
 * @since 1.0
 */
class CErrorHandler extends CApplicationComponent
{
    /**
     * @var integer maximum number of source code lines to be displayed. Defaults to 25.
     */
    public $maxSourceLines=25;

    /**
     * @var integer maximum number of trace source code lines to be displayed. Defaults to 10.
     * @since 1.1.6
     */
    public $maxTraceSourceLines = 10;

    /**
     * @var string the application administrator information (could be a name or email link). It is displayed in error pages to end users. Defaults to 'the webmaster'.
     */
    public $adminInfo='the webmaster';
    /**
     * @var boolean whether to discard any existing page output before error display. Defaults to true.
     */
    public $discardOutput=true;
    /**
     * @var string the route (eg 'site/error') to the controller action that will be used to display external errors.
     * Inside the action, it can retrieve the error information by Yii::app()->errorHandler->error.
     * This property defaults to null, meaning CErrorHandler will handle the error display.
     * @since 1.0.6
     */
    public $errorAction;

    private $_error;

    /**
     * Handles the exception/error event.
     * This method is invoked by the application whenever it captures
     * an exception or PHP error.
     * @param CEvent $event the event containing the exception/error information
     */
    public function handle($event)
    {
        // set event as handled to prevent it from being handled by other event handlers
        $event->handled=true;

        if($this->discardOutput)
        {
            while (ob_get_length())
            @ob_end_clean();
        }

        if($event instanceof CExceptionEvent)
        $this->handleException($event->exception);
        else // CErrorEvent
        $this->handleError($event);
    }

    /**
     * Returns the details about the error that is currently being handled.
     * The error is returned in terms of an array, with the following information:
     * <ul>
     * <li>code - the HTTP status code (e.g. 403, 500)</li>
     * <li>type - the error type (e.g. 'CHttpException', 'PHP Error')</li>
     * <li>message - the error message</li>
     * <li>file - the name of the PHP script file where the error occurs</li>
     * <li>line - the line number of the code where the error occurs</li>
     * <li>trace - the call stack of the error</li>
     * <li>source - the context source code where the error occurs</li>
     * </ul>
     * @return array the error details. Null if there is no error.
     * @since 1.0.6
     */
    public function getError()
    {
        return $this->_error;
    }

    /**
     * Handles the exception.
     * @param Exception $exception the exception captured
     */
    protected function handleException($exception)
    {
        $app=Yii::app();
        if($app instanceof CWebApplication)
        {
            if(($trace=$this->getExactTrace($exception))===null)
            {
                $fileName=$exception->getFile();
                $errorLine=$exception->getLine();
            }
            else
            {
                $fileName=$trace['file'];
                $errorLine=$trace['line'];
            }

            $trace = $exception->getTrace();

            foreach($trace as $i=>$t)
            {
                if(!isset($t['file']))
                $trace[$i]['file']='unknown';

                if(!isset($t['line']))
                $trace[$i]['line']=0;

                if(!isset($t['function']))
                $trace[$i]['function']='unknown';

                unset($trace[$i]['object']);
            }

            $this->_error=$data=array(
				'code'=>($exception instanceof CHttpException)?$exception->statusCode:500,
				'type'=>get_class($exception),
				'errorCode'=>$exception->getCode(),
				'message'=>$exception->getMessage(),
				'file'=>$fileName,
				'line'=>$errorLine,
				'trace'=>$exception->getTraceAsString(),
				'traces'=>$trace,
            );

            if(!headers_sent())
            header("HTTP/1.0 {$data['code']} ".get_class($exception));
            if($this->isAjaxRequest())
            $app->displayException($exception);
            else if($exception instanceof CHttpException || !YII_DEBUG)
            $this->render('error',$data);
            else
            $this->render('exception',$data);
        }
        else
        $app->displayException($exception);
    }

    /**
     * Handles the PHP error.
     * @param CErrorEvent $event the PHP error event
     */
    protected function handleError($event)
    {
        $trace=debug_backtrace();
        // skip the first 3 stacks as they do not tell the error position
        if(count($trace)>3)
        $trace=array_slice($trace,3);
        $traceString='';
        foreach($trace as $i=>$t)
        {
            if(!isset($t['file']))
            $trace[$i]['file']='unknown';

            if(!isset($t['line']))
            $trace[$i]['line']=0;

            if(!isset($t['function']))
            $trace[$i]['function']='unknown';

            $traceString.="#$i {$trace[$i]['file']}({$trace[$i]['line']}): ";
            if(isset($t['object']) && is_object($t['object']))
            $traceString.=get_class($t['object']).'->';
            $traceString.="{$trace[$i]['function']}()\n";

            unset($trace[$i]['object']);
        }

        $app=Yii::app();
        if($app instanceof CWebApplication)
        {
            $this->_error=$data=array(
				'code'=>500,
				'type'=>'PHP Error',
				'message'=>$event->message,
				'file'=>$event->file,
				'line'=>$event->line,
				'trace'=>$traceString,
				'traces'=>$trace,
            );
            if(!headers_sent())
            header("HTTP/1.0 500 PHP Error");
            if($this->isAjaxRequest())
            $app->displayError($event->code,$event->message,$event->file,$event->line);
            else if(YII_DEBUG)
            $this->render('exception',$data);
            else
            $this->render('error',$data);
        }
        else
        $app->displayError($event->code,$event->message,$event->file,$event->line);
    }

    /**
     * whether the current request is an AJAX (XMLHttpRequest) request.
     * @return boolean whether the current request is an AJAX request.
     */
    protected function isAjaxRequest()
    {
        return isset($_SERVER['HTTP_X_REQUESTED_WITH']) && $_SERVER['HTTP_X_REQUESTED_WITH']==='XMLHttpRequest';
    }

    /**
     * Returns the exact trace where the problem occurs.
     * @param Exception $exception the uncaught exception
     * @return array the exact trace where the problem occurs
     */
    protected function getExactTrace($exception)
    {
        $traces=$exception->getTrace();

        foreach($traces as $trace)
        {
            // property access exception
            if(isset($trace['function']) && ($trace['function']==='__get' || $trace['function']==='__set'))
            return $trace;
        }
        return null;
    }

    /**
     * Renders the view.
     * @param string $view the view name (file name without extension).
     * See {@link getViewFile} for how a view file is located given its name.
     * @param array $data data to be passed to the view
     */
    protected function render($view,$data)
    {
        if($view==='error' && $this->errorAction!==null)
        Yii::app()->runController($this->errorAction);
        else
        {
            // additional information to be passed to view
            $data['version']=$this->getVersionInfo();
            $data['time']=time();
            $data['admin']=$this->adminInfo;
            include($this->getViewFile($view,$data['code']));
        }
    }

    /**
     * Determines which view file should be used.
     * @param string $view view name (either 'exception' or 'error')
     * @param integer $code HTTP status code
     * @return string view file path
     */
    protected function getViewFile($view,$code)
    {
        $viewPaths=array(
        Yii::app()->getTheme()===null ? null :  Yii::app()->getTheme()->getSystemViewPath(),
        Yii::app() instanceof CWebApplication ? Yii::app()->getSystemViewPath() : null,
        YII_PATH.DIRECTORY_SEPARATOR.'views',
        );

        foreach($viewPaths as $i=>$viewPath)
        {
            if($viewPath!==null)
            {
                $viewFile=$this->getViewFileInternal($viewPath,$view,$code,$i===2?'en_us':null);
                if(is_file($viewFile))
                return $viewFile;
            }
        }
    }

    /**
     * Looks for the view under the specified directory.
     * @param string $viewPath the directory containing the views
     * @param string $view view name (either 'exception' or 'error')
     * @param integer $code HTTP status code
     * @param string $srcLanguage the language that the view file is in
     * @return string view file path
     */
    protected function getViewFileInternal($viewPath,$view,$code,$srcLanguage=null)
    {
        $app=Yii::app();
        if($view==='error')
        {
            $viewFile=$app->findLocalizedFile($viewPath.DIRECTORY_SEPARATOR."error{$code}.php",$srcLanguage);
            if(!is_file($viewFile))
            $viewFile=$app->findLocalizedFile($viewPath.DIRECTORY_SEPARATOR.'error.php',$srcLanguage);
        }
        else
        $viewFile=$viewPath.DIRECTORY_SEPARATOR."exception.php";
        return $viewFile;
    }

    /**
     * Returns server version information.
     * If the application is in production mode, empty string is returned.
     * @return string server version information. Empty if in production mode.
     */
    protected function getVersionInfo()
    {
        if(YII_DEBUG)
        {
            $version='<a href="http://www.yiiframework.com/">Yii Framework</a>/'.Yii::getVersion();
            if(isset($_SERVER['SERVER_SOFTWARE']))
            $version=$_SERVER['SERVER_SOFTWARE'].' '.$version;
        }
        else
        $version='';
        return $version;
    }

    /**
     * Converts arguments array to its string representation
     *
     * @param array $args arguments array to be converted
     * @return string string representation of the arguments array
     */
    protected function argumentsToString($args)
    {
        $count=0;
        foreach($args as $key => $value)
        {
            $count++;
            if($count>=5)
            {
                if($count>5)
                unset($args[$key]);
                else
                $args[$key]='...';
                continue;
            }

            if(is_object($value))
            $args[$key] = get_class($value);
            else if(is_bool($value))
            $args[$key] = $value ? 'true' : 'false';
            else if(is_string($value))
            {
                if(strlen($value)>64)
                $args[$key] = '"'.substr($value,0,64).'..."';
                else
                $args[$key] = '"'.$value.'"';
            }
            else if(is_array($value))
            $args[$key] = 'array('.$this->argumentsToString($value).')';
            else if($value===null)
            $args[$key] = 'null';
            else if(is_resource($value))
            $args[$key] = 'resource';

            if(is_string($key))
            $args[$key] = '"'.$key.'" => '.$args[$key];
        }
        $out = implode(", ", $args);

        return $out;
    }

    /**
     * Returns a value indicating whether the call stack is from application code.
     * @param array $trace the trace data
     * @return boolean whether the call stack is from application code.
     */
    protected function isCoreCode($trace)
    {
        if(isset($trace['file']))
        {
            $systemPath=realpath(dirname(__FILE__).'/..');
            return $trace['file']==='unknown' || strpos(realpath($trace['file']),$systemPath.DIRECTORY_SEPARATOR)===0;
        }
        return false;
    }

    /**
     * Renders the source code around the error line.
     * @param string $file source file path
     * @param integer $errorLine the error line number
     * @param integer $maxLines maximum number of lines to display
     * @return string the rendering result
     */
    protected function renderSourceCode($file,$errorLine,$maxLines)
    {
        $errorLine--;	// adjust line number to 0-based from 1-based
        if($errorLine<0 || ($lines=@file($file))===false || ($lineCount=count($lines))<=$errorLine)
        return '';

        $halfLines=(int)($maxLines/2);
        $beginLine=$errorLine-$halfLines>0 ? $errorLine-$halfLines:0;
        $endLine=$errorLine+$halfLines<$lineCount?$errorLine+$halfLines:$lineCount-1;
        $lineNumberWidth=strlen($endLine+1);

        $output='';
        for($i=$beginLine;$i<=$endLine;++$i)
        {
            $isErrorLine = $i===$errorLine;
            $code=sprintf("<span class=\"ln".($isErrorLine?' error-ln':'')."\">%0{$lineNumberWidth}d</span> %s",$i+1,CHtml::encode(str_replace("\t",'    ',$lines[$i])));
            if(!$isErrorLine)
            $output.=$code;
            else
            $output.='<span class="error">'.$code.'</span>';
        }
        return '<div class="code"><pre>'.$output.'</pre></div>';
    }
}
